Key points
What is already known on this topic
- The bacteriological profile of the infection of the diabetic foot is essential.
- Altered glucose level delays wound healing thus increasing the severity of ulcers and favor the occurrence of grade II, III, and IV ulcers.
What this study adds
- It was concluded from the study that hemoglobin A1c level was uncontrolled in the majority of the diabetic foot ulcers (DFU) patients, suffering from grade 2 to grade 5.
- Staphylococcus aureus was the most common pathogen of DFU followed by Escherichia coli, Pseudomonas aeruginosa, Enterococcus, and Streptococcus.
Introduction
Infections of the foot are the most prevailing cause of frequent hospital admissions among patients suffering from diabetes as they are prone to develop foot ulcers throughout life1. Amputation of lower limbs due to multiple occurrences of foot ulcers is one of the leading causes of morbidity in diabetics1. Twenty-five percent of people suffering from diabetes are predicted to develop diabetic foot in their lifetime resulting in the expenditure of millions on recovery, recurrent hospitalizations, and disability2. In all, 381.8 million individuals procured diabetes in the year 2013 and the count is expected to rise to 591.9 million by 20353. The incidence of diabetes mellitus (DM) was 5.2 million in Pakistan in 2011, and the predicted rise for 2030 is 14 million4.
Diabetic foot is indicated by multiple complications such as ulcerations5, neuropathy, peripheral vascular disease, infections with or without bone engagement, compromised immune system2,6. The diabetic foot develops ulceration contributory to peripheral neuropathy resulting in a decline of protective sensation, foot abnormalities, gait disorders, and decreased mobility5. Fundamental signs confirming the diagnosis of infection are the presence of at least 2 components of inflammation that is, erythema and purulent secretions7,8. Multiple studies have quoted modifications in demographics of bacteria causing DFU2, due to alterations in causative microorganisms, geography, and severity of infection9. The majority of mild infections have monomicrobial etiology9, while severe infections were a consequence of polymicrobial etiology2,9. S. aureus, a gram-positive coccus is reported by abundant studies as a popular organism followed by Escherichia coli and Klebsiella pneumonia as a root cause of diabetic foot infections10,11. A study regulated in India reported about 22.6% negative wound swabs in Wagner grade II foot infections, and 5.66% of individuals were detected with Methicillin-resistant S. aureus (MRSA). Sufferers with positive wound swab cultures who developed severe infections belonged to Wagner grade III and IV12. P. aeruginosa was prevalent detection of 66.6% wound swabs in grade III infections followed by MRSA with 62.6% and mixed bacteriology with 44.4%12. Wounds categorized in grade IV were frequently infected by mixed bacteria (9.43%), extended-spectrum beta-lactamase Klebsiella (7.55%), MRSA (5.66%), while 80% of grade IV infections have extended-spectrum beta-lactamase Klebsiella positive in their wound cultures13. Maximum wound infections are treated with systemic antibiotics regimen and priority is always given to empirical before culture results14. In the case of mild infections preferred choice of antibiotics is narrow-spectrum antibiotics while broad-spectrum antibiotics are utilized in case of antibiotic-resistant infections, formerly treated and/or severe infections9. Meropenem followed by amikacin and gentamicin are the most effective antibiotics against a variety of organisms detected in wound swabs of DFU, an outcome reported by a study conducted in Pakistan10. Co-trimoxazole followed by cefuroxime and ceftriaxone were reportedly resistant antibiotics10.
In the association of Wagner classification of the diabetic foot, most prevalent is grade III with 35% followed by grade IV (29.9%), grade 0 in 15.6%, grade II in 11.7%, grade I in 6.5%, and grade V in 1.3% of sufferers15. In terms of gram-positive organisms, the most frequently encountered organism detected is S. aureus (28%) seconded by Enterococcus species (8%), Streptococci (4%), and MRSA (4%)16. The majority of gram-negative species isolated from wound cultures revealed the presence of P. aeruginosa (24%), Escherichia coli (8%), K. pneumonia (8%), Proteus vulgaris (4%), Proteus mirabilis (4%), and Acinetobacter (4%), respectively16.
DFU erode every layer of skin in the form of necrosis and gangrene involving soles of feet as a consequence of peripheral neuropathy and peripheral arterial disease in sufferers of DM17,18. Incidence of DFU is propagating increasingly across the globe, but actual incidence differs from region to region, predicted suffering throughout the world is 4%–27%19–21. A diabetic foot ulcer is rendered as an avoidable complication, and plain interventions can decrease the chances of amputation by 80%. Maintaining convenient levels of hemoglobin, blood pressures, and lipids reduces the probability of developing complications of diabetes. Routine assessment and prompt treatment are suitable mechanisms to prevent the development of complications22,23. The aim of our study was to evaluate the current organism growing into the pus cultures of diabetic foot patients and to further document their sensitivity and resistance toward antibiotics.
Materials and methods
This study was conducted among admitted patients in the department of Medicine and Orthopedics, of a tertiary care hospital according to the Helsinki’s protocol and after taking ethical approval (DUH). The duration of the study was 6 months from October 2019 to March 2020. The sample size calculation was done using the Open Epi calculator (https://www.openepi.com/Menu/OE_Menu.htm). The frequency of isolated growth of S. aureus in diabetic foot infections was reported to be 28%24, with a margin of error of 7%, a confidence interval of 95%, and the sample size was calculated to be 139. The sampling was done by the nonprobability consecutive method. The inclusion criteria of this study were known DM since the last 5 years, with a foot ulcer of any grade and culture positive for bacterial growth. Patients taking any antibiotics or immunosuppressants for at least 1 week were excluded from the study, along with nondiabetic patients, already known human immunodeficiency virus (HIV) infected, or not having bacterial growth in our cultures. Data collection procedure included detailed history and examination for diabetic foot, 5 mL venous sample will be taken for HbA1C, and specimen for culture and sensitivity from the wound was obtained by sterile swab at time of admission and will be sent to microbiology laboratory for analysis according to predefined in-hospital protocol. Susceptibility and resistance of microorganisms involved was calculated according to the Clinical & Laboratory Standards Institute (CLSI) guidelines for antibiotic susceptibility testing.
All patients with DFU admitted at Dow University Hospital with a positive bacterial growth were included in the study, and data obtained were assembled by using the software IBM SPSS Statistics for Windows, version 25.0 (Armonk, NY: IBM Corp.). Quantitative variables such as age and HbA1c levels were expressed as mean and SD. Qualitative variables like gender, type of bacteria, antibiotic susceptibility, and resistance were expressed as frequency and/or relative percentage. STROCSS 2021 reporting guidelines were followed to report the study results24.
Results
In Table 1, descriptive statistics of continuous variables are given, with a mean age of 55.27 years, and mean HbA1c levels of 9.51%. A total of 101 (72.66%) patients were males and 38 (27.33%) were females. Male patients were more affected by the disease as compared with female patients. The enrolled patients belonged to different wound grades according to the Wagner classification; in grade 2 there were 48 (34.53%) patients, in grade 3 there were 27 (19.42%) patients, in grade 4 there were 54 (38.84%) patients, and in grade 5 there were 10 (7.19%) patients. In this study, 180 bacteria were isolated from pus cultures of 139 patients. Forty-one cultures had dual bacterial growth. The most frequent bacteria isolated were S. aureus (43.16%), methicillin-resistant staphylococcal aureus (5.03%), Enterococcus species (5.75%), Streptococcus species (7.91%), P. aeruginosa (20.14%), Escherichia coli (24.46%), K. pneumonia 7 (5.03%), P. vulgaris 6 (4.31%), Proteus mirabilis 3 (2.15%), Enterobacter species 7 (5.03%), Morganella morganii 2 (1.43%), and Acinetobacter 7 (5.03%). Growth of S. aureus was found slightly associated with age below 50 (P=0.071), and more likely to occur in grade II wounds with an odds ratio of 3.267 (P=0.060). P. aeruginosa was found significantly associated with grade V wound with an odds ratio of 8.333 (P=0.030), while rest of the organisms were insignificant to sex, age, duration of diabetes, levels of HbA1c or grade of wound as shown in Table 2.
Table 1 -
Showing baseline characteristics of the patients and the frequency of documented organisms within pus cultures.
| Variable |
Mean |
SD |
| Age (y) |
55.27 |
9.64 |
| HbA1c (%) |
9.51 |
2.48 |
| Duration of diabetes |
7.46 |
3.87 |
| Sex |
Frequency |
Percentage |
| Male |
101 |
72.66 |
| Female |
38 |
27.33 |
| Wagner classification |
| Wound grade I |
0 |
0 |
| Wound grade II |
48 |
34.53 |
| Wound grade III |
27 |
19.42 |
| Wound grade IV |
54 |
38.84 |
| Wound grade V |
10 |
7.19 |
| Isolated bacteria |
|
Staphylococcus aureus
|
60 |
43.16 |
| MRSA |
7 |
5.03 |
|
Enterococcus species |
8 |
5.75 |
|
Streptococcus species |
11 |
7.91 |
|
Pseudomonas aeruginosa
|
28 |
20.14 |
|
Escherichia coli
|
34 |
24.46 |
|
Klebsiella pneumonia
|
7 |
5.03 |
|
Proteus vulgaris
|
6 |
4.31 |
|
Proteus mirabilis
|
3 |
2.15 |
|
Enterobacter species |
7 |
5.03 |
|
Morganella morganii
|
2 |
1.43 |
|
Acinetobacter
|
7 |
5.03 |
MRSA indicates Methicillin-resistant S. aureus.
Table 2 -
Factors associated with commonly isolated organisms in the study cultures.
| Factors |
Staphylococcal aureus |
Escherichia coli
|
Pseudomonas aeruginosa
|
Streptococcus Species |
Enterococcus Species |
| Age (<50) |
39 (41.9%) |
18 (19.4%) |
16 (17.2%) |
6 (6.5%) |
3 (3.2%) |
| Age (>50) |
21 (28.4%) |
16 (21.6%) |
12 (16.2%) |
5 (6.8%) |
5 (6.8%) |
| OR (P) |
1.823 (P=0.071) |
0.870 (P=0.718) |
1.074 (P=0.865) |
0.952 (P=0.937) |
0.460 (P=0.299) |
| Sex, male |
42 (41.5%) |
27 (26.7%) |
21(20.8%) |
9 (8.9%) |
7 (6.9%) |
| Sex, female |
18 (47.3%) |
7 (17.9%) |
7 (8.4%) |
2 (5.2%) |
1 (2.5%) |
| OR (P) |
0.549 (P=0.451) |
1.278 (P=0.315) |
0.678 (P=0.317) |
0.730 (P=0.153) |
0.814 (P=0.145) |
| Duration of diabetes, >10 y |
26 (47.3%) |
13 (23.6%) |
15 (27.3%) |
4 (7.3%) |
3 (5.5%) |
| Duration of diabetes, <10 y |
34 (40.5%) |
21 (25.0%) |
13 (15.5%) |
7 (8.3%) |
5 (6.0%) |
| OR (P) |
1.318 (P=0.429) |
1.077 (P=0.855) |
0.488 (P=0.093) |
1.159 (P=0.821) |
1.097 (P=0.902) |
| HbA1c, >9.0% |
40 (51.9%) |
16 (20.8%) |
12 (15.6%) |
5 (6.5%) |
4 (5.2%) |
| HbA1c, <9.0% |
20 (32.3%) |
18 (29.0%) |
16 (25.8%) |
6 (9.7%) |
4 (6.5%) |
| OR (P) |
2.270 (P=0.021) |
1.560 (P=0.262) |
1.884 (P=0.139) |
1.543 (P=0.492) |
1.259 (P=0.752) |
| Wagner grade II |
28 (58.3%) |
11 (22.9%) |
10 (20.8%) |
4 (8.3%) |
3 (6.3%) |
| Wagner grade III |
11 (40.7%) |
6 (22.2%) |
2 (7.4%) |
1 (3.7%) |
1 (3.7%) |
| Wagner grade IV |
18 (33.3%) |
15 (27.8%) |
12 (22.2%) |
5 (9.3%) |
4 (7.4%) |
| Wagner grade V |
3 (30.3%) |
2 (20.0%) |
4 (40.0%) |
1 (10.0%) |
0 (0.0%) |
| OR (P) |
3.267 (P=0.060) |
0.650 (P=0.811) |
8.333 (P=0.030) |
1.089 (P=0.801) |
1.081 (P=0.638) |
Table 2 showing the factors associated with commonly isolated organisms in the study cultures.
The distribution of susceptibility and resistance of different antibiotics against isolated bacteria are shown in Table 3. Staphylococcal aureus, the commonest bacterial growth reported in our study was found highly sensitive to chloramphenicol (85%), followed by vancomycin (70%), clindamycin (68%), amikacin (68%), gentamicin (58%), erythromycin (53%), and tetracycline (53%). The most resistant antibiotics to staphylococcal aureus were penicillin (83%), amoxicillin/clavulanic acid (67%), cloxacillin (67%), fusidic acid (42%), and erythromycin (38%). E. coli was the second common isolated organism, being highly sensitive to amikacin (85%), followed by gentamicin (70%), piperacillin/tazobactam (65%), amoxicillin/clavulanic acid (56%), and meropenem (41%), whereas found most resistant to ampicillin (88%), cefixime (88%), cefuroxime (88%), ceftriaxone (73%), ciprofloxacin (68%), and amoxicillin/clavulanic acid (44%). P. aeruginosa is another frequently detected organism, being sensitive to amikacin (93%), ceftazidime (82%), piperacillin/tazobactam (71%), gentamicin (68%), and ciprofloxacin (64%). The resistant antibiotics were ciprofloxacin (36%), gentamicin (21%), and ceftazidime (18%). About 6 cultures growing P. aeruginosa were pan-resistant (only sensitive to colomycin). MRSA was most sensitive to vancomycin followed by amikacin and resistant to cloxacillin and amoxicillin/clavulanic acid. Ampicillin, amoxicillin/clavulanic acid, and chloramphenicol were most sensitive to Enterococcus species while levofloxacin was resistant. Amoxicillin/clavulanic acid was sensitive for streptococcal species with co-trimoxazole (trimethoprim/sulfamethoxazole) being resistant. Amikacin was mostly sensitive to K. pneumonia with cefuroxime being the most resistant antibiotic. P. mirabilis is usually pan-sensitive, but P. vulgaris has shown maximum resistance to cefuroxime with maximum sensitivity to meropenem and amikacin. Acinetobacter was found to be the most pan-resistant organism showing sensitivity only to colomycin (86%), and maximum resistance to cefuroxime, levofloxacin, and sulbactam/cefoperazone. Enterobacter was resistant to all generations of cephalosporins while being sensitive to colomycin and polymyxin B. Lastly, the least encountered organism was M. morganii showing sensitivity to piperacillin/tazobactam and resistance to ampicillin and amoxicillin/clavulanic acid.
Table 3 -
Showing the frequency of susceptibility of microorganisms to antibiotics isolated in the cultures.
|
Organisms |
| Antibiotics |
1. Staph aureus |
2. MRSA |
3. Enterococcus
|
4. Streptococcus
|
5. P. aeruginosa
|
6. E. coli
|
7. K. pneumonia
|
8. Proteus Mirabilis |
9. Acinetobacter |
10. Proteus Vulgaris |
11. Enterobacter |
12. Morganella Morganii
|
| Aztreonam |
| Sensitive (n=1) |
— |
— |
— |
0 |
— |
— |
— |
— |
— |
— |
— |
1 |
| Resistant (n=1) |
— |
— |
— |
1 |
— |
— |
— |
— |
— |
— |
— |
0 |
| Amikacin |
| Sensitive (n=125) |
41 |
5 |
3 |
2 |
26*
|
29*
|
6*
|
3*
|
3 |
4*
|
3 |
— |
| Resistant (n=39) |
18 |
2 |
0 |
1 |
2 |
5 |
1 |
0 |
4 |
2 |
4 |
— |
| Amoxicillin/ Clavulanic acid |
| Sensitive (n=61) |
19 |
0 |
4*
|
10*
|
— |
19 |
4 |
3*
|
— |
2 |
— |
0 |
| Resistant (n=70) |
40 |
5 |
1 |
0 |
— |
15 |
3 |
0 |
— |
4 |
— |
2†
|
| Ampicillin |
| Sensitive (n=16) |
— |
— |
4*
|
8 |
— |
2 |
0 |
2 |
— |
0 |
— |
0 |
| Resistant (n=39) |
— |
— |
3†
|
0 |
— |
30†
|
1 |
1†
|
— |
2 |
— |
2†
|
| Ciprofloxacin |
| Sensitive (n=38) |
— |
0 |
0 |
— |
18 |
11 |
1 |
3*
|
1 |
3 |
1 |
— |
| Resistant (n=57) |
— |
2 |
1 |
— |
10†
|
23 |
6 |
0 |
6 |
3 |
6†
|
— |
| Ceftriaxone |
| Sensitive (n=19) |
— |
— |
0 |
5 |
— |
7 |
1 |
3*
|
0 |
2 |
1 |
0 |
| Resistant (n=50) |
— |
— |
1 |
0 |
— |
25 |
6 |
0 |
7†
|
4 |
6†
|
1 |
| Cefixime |
| Sensitive (n=7) |
— |
— |
0 |
— |
— |
3 |
0 |
3*
|
— |
0 |
1 |
— |
| Resistant (n=63) |
— |
— |
1 |
— |
— |
30†
|
6 |
0 |
— |
2 |
6†
|
— |
| Cefuroxime |
| Sensitive (n=6) |
— |
— |
0 |
— |
— |
3 |
0 |
2 |
0 |
0 |
1 |
0 |
| Resistant (n=54) |
— |
— |
2 |
— |
— |
30†
|
7†
|
1†
|
1 |
6†
|
6†
|
1 |
| Trimethoprim/ Sulfamethoxazole |
| Sensitive (n=24) |
10 |
— |
0 |
1 |
— |
7 |
2 |
2 |
0 |
0 |
2 |
— |
| Resistant (n=44) |
18 |
— |
2 |
4†
|
— |
12 |
2 |
0 |
3 |
2 |
1 |
— |
| Gentamicin |
| Sensitive (n=93) |
35 |
2 |
0 |
1 |
19 |
24 |
3 |
3*
|
1 |
2 |
3 |
— |
| Resistant (n=50) |
20 |
2 |
1 |
1 |
6 |
6 |
2 |
0 |
4 |
4 |
4 |
— |
| Meropenem |
| Sensitive (n=32) |
— |
— |
1 |
— |
7 |
14 |
3 |
— |
1 |
4*
|
2 |
0 |
| Resistant (n=11) |
— |
— |
0 |
— |
3 |
1 |
0 |
— |
3 |
0 |
3 |
1 |
| Piperacillin/ Tazobactam |
| Sensitive (n=54) |
— |
— |
0 |
— |
20 |
22 |
3 |
3*
|
0 |
3 |
1 |
2*
|
| Resistant (n=18) |
— |
— |
1 |
— |
2 |
6 |
1 |
0 |
3 |
1 |
4 |
0 |
| Vancomycin |
| Sensitive (n=52) |
42 |
6*
|
3 |
1 |
— |
— |
0 |
— |
— |
— |
— |
— |
| Resistant (n=4) |
1 |
0 |
2 |
0 |
— |
— |
1 |
— |
— |
— |
— |
— |
| Levofloxacin |
| Sensitive (n=8) |
— |
— |
2 |
6 |
— |
0 |
0 |
— |
0 |
— |
0 |
— |
| Resistant (n=13) |
— |
— |
3†
|
0 |
— |
1 |
1 |
— |
5 |
— |
3 |
— |
| Clindamycin |
| Sensitive (n=45) |
41 |
— |
— |
4 |
— |
— |
— |
— |
— |
— |
— |
— |
| Resistant (n=18) |
16 |
— |
— |
2 |
— |
— |
— |
— |
— |
— |
— |
— |
| Polymyxin B |
| Sensitive (n=10) |
— |
— |
— |
— |
3 |
— |
— |
— |
3 |
— |
4*
|
— |
| Resistant (n=0) |
— |
— |
— |
— |
0 |
— |
— |
— |
0 |
— |
0 |
— |
| Colomycin |
| Sensitive (n=20) |
— |
— |
— |
— |
6 |
2 |
2 |
— |
6*
|
— |
4*
|
— |
| Resistant (n=0) |
— |
— |
— |
— |
0 |
0 |
0 |
— |
0 |
— |
0 |
— |
| Tobramycin |
| Sensitive (n=1) |
— |
— |
— |
— |
0 |
— |
— |
— |
1 |
— |
0 |
— |
| Resistant (n=7) |
— |
— |
— |
— |
3 |
— |
— |
— |
1 |
- |
3 |
- |
| Ceftazidime |
| Sensitive (n=23) |
0 |
— |
— |
— |
23 |
— |
— |
— |
— |
— |
— |
0 |
| Resistant (n=7) |
1 |
— |
— |
— |
5 |
— |
— |
— |
— |
— |
— |
1 |
| Sulbactam/ Cefoperazone |
| Sensitive (n=3) |
— |
— |
— |
0 |
1 |
0 |
0 |
— |
1 |
— |
0 |
1 |
| Resistant (n=12) |
— |
— |
— |
0 |
0 |
2 |
2 |
— |
5 |
— |
3 |
0 |
| Cloxacillin |
| Sensitive (n=16) |
16 |
0 |
— |
0 |
0 |
— |
— |
— |
— |
— |
— |
— |
| Resistant (n=48) |
40 |
7†
|
— |
1 |
0 |
— |
— |
— |
— |
— |
— |
— |
| Chloramphenicol |
| Sensitive (n=65) |
51*
|
— |
4*
|
9 |
— |
— |
— |
— |
— |
— |
— |
1 |
| Resistant (n=4) |
3 |
— |
0 |
1 |
— |
— |
— |
— |
— |
— |
— |
0 |
| Erythromycin |
| Sensitive (n=39) |
32 |
— |
3 |
4 |
— |
— |
— |
— |
— |
— |
— |
0 |
| Resistant (n=28) |
23 |
— |
2 |
2 |
— |
— |
— |
— |
— |
— |
— |
1 |
| Fusidic acid |
| Sensitive (n=17) |
17 |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| Resistant (n=25) |
25 |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| Penicillin |
| Sensitive (n=1) |
0 |
— |
— |
0 |
1 |
— |
— |
— |
— |
— |
— |
— |
| Resistant (n=51) |
50†
|
— |
— |
1 |
0 |
— |
— |
— |
— |
— |
— |
— |
| Tetracycline |
| Sensitive (n=40) |
32 |
— |
2 |
6 |
— |
— |
— |
— |
0 |
— |
— |
— |
| Resistant (n=18) |
16 |
— |
1 |
0 |
— |
— |
— |
— |
1 |
— |
— |
— |
| Tigecycline |
| Sensitive (n=1) |
— |
— |
1 |
— |
— |
— |
— |
— |
0 |
— |
— |
— |
| Resistant (n=1) |
— |
— |
0 |
— |
— |
— |
— |
— |
1 |
— |
— |
— |
| Minocycline |
| Sensitive (n=4) |
— |
— |
— |
— |
— |
— |
— |
— |
4 |
— |
— |
— |
| Resistant (n=0) |
— |
— |
— |
— |
— |
— |
— |
— |
0 |
— |
— |
— |
— indicates susceptibility not checked for the particular antibiotic, and n= total number of either sensitivity or resistance scored among all isolated bacteria.
Organisms: 1: Staphylococcal aureus (n=60), 2: Methicillin-resistant staphylococcal aureus (n=7), 3: Enterococcus species (n=8), 4: Streptococcus species (n=11), 5: Pseudomonas aeruginosa (n=28), 6: Escherichia coli (n=34), 7: Klebsiella pneumonia (n=7), 8: Proteus mirabilis (n=3), 9: Acinetobacter species (n=7), 10: Proteus vulgaris (n=6), 11: Enterobacter species (n=7), 12: Morganella morganii (n=2).
*Indicates most sensitive antibiotic amongst a particular organism.
†Indicates most resistant antibiotic among a particular organism.
Discussion
DM is a prevailing disease in Pakistan with DFU is a common complication, resulting in morbidity and frequent amputations. Henceforth, the current study is regulated to decipher the bacteriological demography of diabetic foot infection in order to combat it with targeted and efficacious treatment to prevent complications.
In our study, 139 patients suffering from diabetic foot were included for assessment of hemoglobin A1c levels, grades of the wound, and bacteriological growth, with a mean age of 55.27 years, and the majority of participants were males (72%). Akhi et al2 quoted 76% affinity of occurrence of the diabetic foot toward male sex with a mean age of 52.1 years. Another study regulated in a similar accord by Shahi et al19 reported mirroring the high prevalence of male diabetic patients suffering from DFU that is, 71.13% with a mean age of 55.26 years. The majority of studies reported the male sex being more susceptible to developing DFU when compared with females. The outcomes of our study coincided with results of similar studies conducted by Akhi et al2 and Shanmugam and Jeya9, several other researchers quoted most of the patients with age below 50 developing DFU.
Outcomes of our study concluded the majority of diabetic foot patients suffered from wound grade IV (36%), seconded by grade II (30% patients), grade III with 19% patients, and grade V with 7% patients. Correspondingly, Shahi et al19 concluded the increased prevalence of grade III with 31.06% patients followed by grade II with 27.18% patients, grade IV with 26.21% patients, and grade I with 14.56% patients. Our study had no patient from Wagner grade I with a culture positive.
In our study, 180 bacteria were segregated from 139 cultures with 41 patients showing dual isolated bacterial growth. S. aureus was the most prevalent bacteria, followed by Escherichia coli, P. aeruginosa, Enterococcus, Streptococcus, K. pneumonia, Enterobacter, MRSA, P. vulgaris, P. mirabilis, Acinetobacter, and M. morganii was least frequently isolated in that order. Akhi et al2, Abdulrazak et al25, and El-Tahawy26 reported the S. aureus as a common bacterial pathogen causing DFU, whereas Ako-Nai et al27 concluded P. aeruginosa being the most common pathogen. Variations in the prevalence of pathogens were concluded due to different modes of the source of infection, utilization of antibiotic drugs for treatment, methods of sample collection, and various types of infections.
S. aureus is reportedly sensitive to oxacillin (100%), co-trimoxazole (Trimethoprim/Sulfamethoxazole) (100%), gentamicin (83.3%), amoxicillin/clavulanic acid (71.4%), cefuroxime (71.4%), clindamycin (71.4%), erythromycin (71.4%), and ampicillin with 28.5%16. This pattern was contrasted with our study as chloramphenicol, vancomycin, and amikacin were leading sensitivity in our results, while penicillins, amoxicillin/clavulanic acid, and fusidic acid showed high resistance. Enterococcus family is sensitive to Chloramphenicol, amoxicillin/clavulanic acid, doxycycline, and gentamicin16, while resistant to vancomycin (42.8%) and erythromycin (71.4%)2. In our study chloramphenicol was sensitive but levofloxacin showed the most resistance to enterococci. Streptococcus species showed sensitivity to ampicillin, ciprofloxacin, co-trimoxazole, and gentamicin16. But in our study, amoxicillin/clavulanic acid was sensitive to streptococcal species, and co-trimoxazole was resistant. MRSA is responsive to Doxycycline, linezolid, and co-trimoxazole according to one study contrasting our findings of vancomycin followed by amikacin being most sensitive16. P. aeruginosa showed responsiveness to meropenem (100%), aztreonam (100%), ciprofloxacin (83%), tobramycin (67%), and amikacin (67%)16, while resistance was observed to gentamicin (12%) and piperacillin/tazobactam (7%) accordingly28. Our study showed amikacin, ceftazidime, and piperacillin/tazobactam being sensitive to P. aeruginosa with 6 cultures sensitive only to colomycin (pan-resistant). Escherichia coli reactivity to meropenem and piperacillin-tazobactam was reported 100% in a study16, while we observed amikacin (85%), gentamicin (70%), piperacillin/tazobactam (65%), amoxicillin/clavulanic acid (56%), and meropenem (41%) sensitive. K. pneumonia susceptibility was attributed to amikacin, ciprofloxacin, gentamicin, and piperacillin/tazobactam16 as similar to our study showing amikacin most sensitive to K. pneumonia and cefuroxime most resistant antibiotic. P. vulgaris reactivity is maximum to amikacin, aztreonam, ciprofloxacin, sulbactam/cefoperazone, meropenem, and piperacillin/tazobactam16, similar to our results also showing cefuroxime mostly resistant. P. mirabilis susceptibility to amikacin, sulbactam/cefoperazone, and meropenem is reported in a study whereas we found it pan-sensitive with only one isolated organism showing resistance to ampicillin and cefuroxime16. Lastly, acinetobacter was detected as a pan-resistant organism with similar results in our study showing sensitivity only to colomycin16.
Only one study reported polymicrobial growth in pus cultures occurring more frequently than single isolated organisms, as opposed to our findings29. These polymicrobial reportedly included Escherichia coli as the most frequently growing organism followed by staphylococcal aureus, K. pneumonia, P. aeruginosa, and streptococcus pyogenes29. The limitations of the study included lack of adjustment for confounders like glycemic index and peripheral vascular disease. The maximum number of patients are with Grade 3 wound, which means these effects the bone. Pus cultures are not of benefit in this group of patients, rather bone biopsy and cultures/deep cultures would be a better way to assess the bacteriological profile which were not available in the current study. Furthermore, superficial pus cultures of DFU are not very helpful as they might be contaminated.
Conclusions
Prevalence of DM is high in the Pakistani population and the diabetic foot is one of its major complications. Amputation is a long-term complication of this condition that may increase morbidity in such patients. It is important to recognize the bacteriological profile of diabetic foot infection so that prompt effective treatment could be offered and complications can be prevented. Previously a study from the local population comprised of a small sample size. Therefore, this study will determine the bacteriological profiles in DFU according to their susceptibility on a larger scale. This may be helpful to provide effective treatment to diabetic foot patients and allow to pay attention to diabetic balance in association with appropriate antibiotic therapy in order to optimally manage the diabetic foot.
Ethical approval
Ethical approval was taken in this study from the institutional review board, and consent to participate was not needed due to retrospective nature of the study.
Sources of funding
This work is not supported by any sponsors. No funding required in this study.
Author contribution
M.S.A., M.S., and A.M.: conception of the study, major drafting of the work, final approval and agreeing to the accuracy of the work. O.P. and S.K.: supervision, critical revision of the manuscript, final approval and agreeing to the accuracy of the work. F.N.U.S.: data curation, acquisition, final approval and agreeing to the accuracy of the work. K.K., F.K., N.C., and N.A.: help in design of the study, drafting of the work, final approval and agreeing to the accuracy of the work.
Conflicts of interest disclosure
The authors declare that they have no financial conflict of interest with regard to the content of this report.
Research registration unique identifying number (UIN)
None.
Guarantor
Muhammad Sohaib Asghar.
References
1. Spichler A, Hurwitz BL, Armstrong DG, et al. Microbiology of diabetic foot infections: from Louis Pasteur to “crime scene investigation”. BMC Med 2015;13:1–13.
2. Akhi MT, Ghotaslou R, Asgharzadeh M, et al. Bacterial etiology and antibiotic susceptibility pattern of diabetic foot infections in Tabriz, Iran. GMS Hyg Infect Control 2015;10:1–6.
3. Guariguata L, Whiting DR, Hambleton I, et al. Global estimates of diabetes prevalence for 2013 and projections for 2035. Diabetes Res Clin Pract 2014;103:137–49.
4. Hussain A, Ali I. Diabetes mellitus in Pakistan: a major public health concern. Arch Pharm Pract 2016;7:30–32.
5. Uckay I, Aragon-Sanchez J, Lew D, et al. Diabetic foot infections: what have we learned in the last 30 years? Int J Infect Dis 2015;40:81–91.
6. Quilici MT, Del Fiol Fde S, Vieira AE, et al. Risk factors for foot amputation in patients hospitalized for diabetic foot infection. J Diabetes Res 2016;2016:1–8.
7. Schaper NC, Van Netten JJ, Apelqvist J, et al. Prevention and management of foot problems in diabetes: a summary guidance for daily practice 2015, based on the IWGDF guidance documents. Diabetes Metab Res Rev 2016;32:7–15.
8. Lipsky BA, Berendt AR, Cornia PB, et al. 2012 Infectious diseases society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. Clin Infect Dis 2012;54:132–74.
9. Shanmugam P, Jeya M. The bacteriology of diabetic foot ulcers, with a special reference to multidrug resistant strains. J Clin Diagn Res 2013;7:441–5.
10. Nageen A. The most prevalent organism in diabetic foot ulcers and its drug sensitivity and resistance to different standard antibiotics. J Coll Phys Surg Pak 2016;26:293–6.
11. Ayub R, Raza SS, Shafiullah JA, et al. Bacterial culture isolates from infected diabetic foot tissue specimens and their sensitivity to antimicrobial agents. J Med Sci 2016;24:273–7.
12. Pal B, Gupta SK. A study on the relation of the severity of diabetic foot ulcers with the type of bacterial flora isolated from the wounds. Int Surg J 2016;3:189–94.
13. Mottola C, Matias CS, Mendes JJ, et al. Susceptibility patterns of
Staphylococcus aureus biofilms in diabetic foot infections. BMC Microbiol 2016;16:1–9.
14. Gardner SE, Haleem A, Jao YL, et al. Cultures of diabetic foot ulcers without clinical signs of infection do not predict outcomes. Diabetes Care 2014;37:2693–701.
15. Nur AH, Intan NS, Syafinaz AN, et al. Clinical presentation and microorganisms sensitivity profile for diabetic foot ulcers: a pilot study. Med J Malaysia 2015;70:182–7.
16. Sekhar SM, Vyas N, Unnikrishnan MK, et al. Antimicrobial susceptibility pattern in diabetic foot ulcer: a pilot study. Ann Med Health Sci Res 2014;4:742–5.
17. Alavi A, Sibbald RG, Mayer D, et al. Diabetic foot ulcers: part I. pathophysiology and prevention. J Am Acad Dermatol 2014;70:1–18.
18. Wang AH, Xu ZR, Ji LN. Clinical characteristics and medical costs of diabetics with amputation at central urban hospitals in China. Zhonghua Yi Xue Za Zhi 2012;92:224–7.
19. Shahi SK, Kumar A, Kumar S, et al. Prevalence of diabetic foot ulcer and associated risk factors in diabetic patients from north India. J Diabetic Foot Complicat 2012;4:83–91.
20. Richard JL, Schuldiner S. Epidemiology of diabetic foot problems. Rev Med Interne 2008;29:222–30.
21. Nather A, Bee CS, Huak CY, et al. Epidemiology of diabetic foot problems and predictive factors for limb loss. J Diabetes Complications 2008;22:77–82.
22. Croxson S. Diabetes in the elderly: problems of care and service provision. Diabet Med 2002;19:66–72.
23. Stumvoll M, Goldstein BJ, van Haeften TW. Type 2 diabetes: principles of pathogenesis and therapy. Lancet 2005;365:1333–46.
24. Mathew G, Agha R. STROCSS 2021: Strengthening the reporting of cohort, cross-sectional and case-control studies in surgery. Ann Med Surg 2021;72:103026.
25. Abdulrazak A, Bitar ZI, Al-Shamali AA, et al. Bacteriological study of diabetic foot infections. J Diabetes Complications 2005;19:138–41.
26. El-Tahawy AT. Bacteriology of diabetic foot. Saudi Med J 2000;21:344–7.
27. Ako-Nai A, Ikem I, Akinloye O, et al. Characterization of bacterial isolates from diabetic foot infections in Ile-Ife, southwestern Nigeria. Foot (Edinb) 2006;16:158–64.
28. Al Benwan K, Al Mulla A, Rotimi VO. A study of the microbiology of diabetic foot infections in a teaching hospital in Kuwait. J Infect Public Health 2012;5:1–8.
29. Kaimkhani GM, Siddiqui AA, Rasheed N N, et al. Pattern of infecting microorganisms and their susceptibility to antimicrobial drugs in patients with diabetic foot infections in a tertiary care hospital in Karachi, Pakistan. Cureus 2018;10:1–8.
